<style>
    #box1
    {
    width: 400px;
    padding: 40px;
    border: 8px double black;
    box-sizing: border-box;
    }
    #box2
    {
    width: 400px;
    border: 8px double black;
    padding: 40px;
    }
</style>
<h1 id="box1"> Box with box-sizing defined</h1>
<h1 id="box2"> Generic Box</h1>